The difficult choices in genetic engineering are only just beginning

The genie is out of the bottle. However particular the case, the decision of Mr and Mrs Nash of Colorado to choose between embryos to produce a second child whose cells could be transplanted to their mortally ill first-born has taken the whole debate over eugenics into a different dimension. New life is for the first time being created for the purpose of helping another life. The vision of the "designer baby" and the nightmare of new beings created solely to help old looms menacingly at the end of a road of rapidly developing genetic science.

The genie is out of the bottle. However particular the case, the decision of Mr and Mrs Nash of Colorado to choose between embryos to produce a second child whose cells could be transplanted to their mortally ill first-born has taken the whole debate over eugenics into a different dimension. New life is for the first time being created for the purpose of helping another life. The vision of the "designer baby" and the nightmare of new beings created solely to help old looms menacingly at the end of a road of rapidly developing genetic science.

Before the moralists leap on the high horse of absolute principle, however, it is worth remembering two points. One is that, in this case, the primary purpose of choosing between embryos was to ensure that the second child was not born with the same life-threatening disease as the first. The question of choosing between the disease-free embryos to find one with tissues matching those of the first-born, Molly, came as an additional benefit. "If one can choose, why not choose an embryo which can help the sister?"

It is also important to remember that choosing between embryos to cut out an inherited disease is already a well-established practice in Britain and elsewhere. Any parents can go to a registered IVF clinic and, provided that the disease is one for which the clinic is licensed to screen, the clinic will dispose of embryos carrying the disease and implant one that doesn't.

That is always the problem of jumping too readily from the specific to the general. Within the confines of this family, facing the likely death of their first child and wanting a second, the choices they made were both reasonable. Within the confines of what has already happened with IVF, it was not even that drastic. But in publicising what they have done, both the doctors and the parents in this case are quite clearly encouraging others to follow suit.

In the end, societies can move only case by case. As long as the technology makes genetic manipulation possible, and people want it, then it will develop, whatever churches or governments may say. So far, Britain has followed a sensible course in establishing a governing body, the Human Fertilisation and Embryology Authority, which can set the limits of what is not permissible and decide, on individual application, what is. It is a moving target. The authority is now in the middle of a consultation process for developing the rules (tellingly, perhaps, the document does not discuss cases such as this).

That must be the right approach. Technology is moving so fast that rules will always have difficulty in keeping pace. Contexts can be established only through consensus, or, as in the case of abortion in the old days, things will proceed in back rooms with no regulation at all. The medical profession needs to move at a pace that society at large can understand and agree with. But equally, society has to accept that parents have a right to, and the doctors should seek to provide, whatever is possible to help their own progeny.

In this particular case, most people would sympathise with the Nashes in the knowledge that they would make the same decision if it were up to them. But what will public opinion be when the parents want an embryo primarily for tissue transplant for themselves or, in the case reported today, the parents wish to choose the embryo on the basis of its sex?